1. Field of the Invention
The present invention relates to a multilayer printed wiring board and a component mounting method thereof, and more particularly to a multilayer printed wiring board capable of mounting a plurality of components and a component mounting method thereof.
2. Description of the Related Art
Multilayer printed wiring boards of the system for mounting components on both surfaces of a printed wiring board (double-sided mounting system) are widely used as a demand for higher performance is increased and surface-mounting technologies are developed increasingly. With respect to the double-sided surface-mounting multilayer printed wiring board, the assignee of the present application has already filed a patent application which is disclosed in the following Patent Document 1.                [Patent Document 1]: Japanese Patent Laid-open Publication No. 2001-339006 “MULTILAYER PRINTED WIRING BOARD” (published on Dec. 7, 2001).        
FIG. 9 in the Patent Document 1 and the description (paragraph [0055]) of the relating patent specification read as follows. That is, an IC chip 90 and a chip capacitor 120 are mounted on the front of a multilayer printed wiring board 10 by solders and a conductive connection pin 180 is mounted on the back of the multilayer printed wiring board by solders. Here, a solder bump 176 to connect the IC chip 90 mounted on the surface of the multilayer printed wiring board is made of a solder of which composition is Sn/Pb, Sn/Ag or Sn/Ag/Cu. Melting points thereof are between 190 and 220° C. and reflow temperatures thereof are between 200 and 230° C. On the other hand, the solder 186 to connect the chip capacitor 120 mounted on the front of the multilayer printed wiring board and the conductive connection pin 180 mounted on the back of the multilayer printed wiring board is made of Sn/Sb solder, both of Sn and Sb having melting points ranging of from 247 to 254° C. (see No. 2 in FIG. 11).